Soybean mosaic virus(SMV),an RNA virus,is the most common and destructive pathogenic virus in soybean fields.The newly developed CRISPR/Cas immune system has provided a novel strategy for improving plant resistance to...Soybean mosaic virus(SMV),an RNA virus,is the most common and destructive pathogenic virus in soybean fields.The newly developed CRISPR/Cas immune system has provided a novel strategy for improving plant resistance to viruses;hence,this study aimed to engineer SMV resistance in soybean using this system.Specifically,multiple sgRNAs were designed to target positive-and/or negative-sense strands of the SMV HC-Pro gene.Subsequently,the corresponding CRISPR/CasRx vectors were constructed and transformed into soybeans.After inoculation with SMV,39.02%,35.77%,and 18.70%of T_(1)plants were confirmed to be highly resistant(HR),resistant(R),and mildly resistant(MR)to SMV,respectively,whereas only 6.50%were identified as susceptible(S).Additionally,qRT-PCR and DAS-ELISA showed that,both at 15 and 30 d post-inoculation(dpi),SMV accumulation significantly decreased or was even undetectable in HR and R plants,followed by MR and S plants.Additionally,the expression level of the CasRx gene varied in almost all T_(1)plants with different resistance level,both at 15 and 30 dpi.Furthermore,when SMV resistance was evaluated in the T_(2)generation,the results were similar to those recorded for the T_(1)generation.These findings provide new insights into the application of the CRISPR/CasRx system for soybean improvement and offer a promising alternative strategy for breeding for resistance to biotic stress that will contribute to the development of SMV-immune soybean germplasm to accelerate progress towards greater soybean crop productivity.展开更多
Soybean(Glycine max)is a major oil and feed crop worldwide.Soybean mosaic virus(SMV)is a globally occurring disease that severely reduces the yield and quality of soybean.Here,we characterized the role of the clock ge...Soybean(Glycine max)is a major oil and feed crop worldwide.Soybean mosaic virus(SMV)is a globally occurring disease that severely reduces the yield and quality of soybean.Here,we characterized the role of the clock gene TIMING OF CAB EXPRESSION 1b(GmTOC1b)in the resistance of soybean to SMV.Homozygous Gmtoc1b mutants exhibited increased tolerance to SMV strain SC3 due to the activation of programmed cell death triggered by a hypersensitive response.Transcriptome deep sequencing and RT-qPCR analysis suggested that GmTOC1b likely regulates the expression of target genes involved in the salicylic acid(SA)signaling pathway.GmTOC1b binds to the promoter of GmWRKY40,which encodes a protein that activates the expression of SA-mediated defense-related genes.Moreover,we revealed that the GmTOC1bH1 haplotype,which confers increased tolerance to SMV,was artificially selected in improved cultivars from the Northern and Huang-Huai regions of China.Our results therefore identify a previously unknown SMV resistance component that could be deployed in the molecular breeding of soybean to enhance SMV resistance.展开更多
Soybean mosaic virus (SMV) causes one of the most severe viral diseases in soybean ( Glycine max L.) and is known to contain many pathogenically and serologically related isolates. In the present study, the authors...Soybean mosaic virus (SMV) causes one of the most severe viral diseases in soybean ( Glycine max L.) and is known to contain many pathogenically and serologically related isolates. In the present study, the authors have obtained cDNAs to all cistrons of a Chinese SMV isolate, SMV_ZK, by RT_PCR. By analysing the nucleotide and amino acid sequence of the HC_PRO, NIb and CP cistrons, it was found that SMV_ZK was highly homologous to the G2 strain of SMV, thus confirming the existence of G2_like isolates in soybean crop in China. The amplified cDNAs were directly cloned into a bacterial expression vector. With the exception of the P3 cistron, expression of the cDNAs of all other cistrons in bacteria gave rise to polypeptides of expected molecular weight. The expressed viral proteins were subsequently purified by gel elution. The preparation of viral_specific cDNAs and gene products will be useful in future functional study of the SMV genome.展开更多
Soybean mosaic virus (SMV) disease is one of the most destructive viral diseases in soybean (Glycine max (L.) Merr.). SMV strain SC3 is the major prevalent strain in huang-huai and Yangtze valleys, China. The so...Soybean mosaic virus (SMV) disease is one of the most destructive viral diseases in soybean (Glycine max (L.) Merr.). SMV strain SC3 is the major prevalent strain in huang-huai and Yangtze valleys, China. The soybean cultivar Qihuang 1 is of a rich resistance spectrum and has a wide range of application in breeding programs in China. In this study, F1, F2 and F2:3 from Qihuang 1×nannong 1138-2 were used to study inheritance and linkage mapping of the SC3 resistance gene in Qihuang 1. The secondary F2 population and near isogenic lines (nILs) derived from residual heterozygous lines (RhLs) of Qihuang 1×nannong 1138-2 were separatively used in the ifne mapping and candidate gene analysis of the resistance gene. Results indicated that a single dominant gene (designated RSC3Q) controls resistance, which was located on chromosome 13. Two genomic-simple sequence repeat (SSR) markers BARCSOYSSR_13_1114 and BARCSOYSSR_13_1136 were found lfanking the two sides of the RSC3Q. The interval between the two markers was 651 kb. Quantitative real-time PCR analysis of the candidate genes showed that ifve genes (Glyma13g25730, 25750, 25950, 25970 and 26000) were likely involved in soybean SMV resistance. These results would have utility in cloning of RSC3Q resistance candidate gene and marker-assisted selection (MaS) in resistance breeding to SMV.展开更多
A sample composed of 96 soybean accessions was evaluated for their diseased rate (I),diseased rank (S), latent period (LP) and rate of disease development (R) in order tostudy the quantitative resistance to soybean mo...A sample composed of 96 soybean accessions was evaluated for their diseased rate (I),diseased rank (S), latent period (LP) and rate of disease development (R) in order tostudy the quantitative resistance to soybean mosaic virus (SMV) in soybeans. The resultsshowed that the performances of the above four resistance components were significantlydifferent among accessions and that some of the accessions, such as Zhongzihuangdou,Peixian Tianedan, Youbian30 could be infected by four SMV strains, Sa, SC8, N1 and N3,but their I, S, and R were lower and LP longer than most other accessions. These resultsdemonstrated the existence of quantitative resistance to SMV in soybeans. It was foundthat some soybean accessions, such as AGS19 and Lishui Zhongzihuangdou, previouslyidentified as resistant to SMV infection, performed some infection but resistant toexpansion in the present study. In addition, the resistance in Pixian Chadou and HuaiyinQiuheidou might be either qualitative or quantitative. Furthermore, the present studyalso indicated that the resistance spectrum and durability of accessions with quantitativeresistance might be wider and longer than those with qualitative resistance.展开更多
Soybean mosaic virus (SMV) is one of the major viral pathogens affecting soybean crops worldwide. Three SMV resistance genes, Rsc4, Rsc8, and Rsc14Q, have been identified and mapped on soybean chromosomes 14, 2, and...Soybean mosaic virus (SMV) is one of the major viral pathogens affecting soybean crops worldwide. Three SMV resistance genes, Rsc4, Rsc8, and Rsc14Q, have been identified and mapped on soybean chromosomes 14, 2, and 13 from Dabaima, Kefeng 1, and Qihuang 1 cultivars, respectively. Soybean cultivar Nannong 1138-2 is widely grown in the Yangtze River Valley of China. In this study, crosses were made between Qihuang l^Kefeng 1 and DabaimaxNannong 1138-2. Ten simple sequence repeat (SSR) markers linked to three resistance loci (Rsc4, Rsc8, and Rsc^4Q) were used to assist pyramided breeding. Pyramided families containing three resistance loci (Rsc4, Rsc8, and Rsc14Q) were evaluated by inoculating them with 21 SMV strains from China. Results indicated that the 10 markers can be used effectively to assist the selection of resistant individuals containing Rsc4, Rsc8, and Rsc14Q. A total of 53 F6 plants were confirmed to contain three homozygous alleles conferring resistance to SMV. Five F7 homozygous pyramided families exhibited resistance to 21 strains of SMV and showed desirable agronomic traits using dual selection. The strategy of pyramiding resistance gene derived from different varieties has practical breeding value in providing broad-spectrum resistance against the existing strains of SMV in China.展开更多
The main defense response to Soybean mosaic virus(SMV)infection in soybean[Glycine max(L.)Merr.]is thought to be blockage of intercellular virus transport by callose deposition on plasmodesmata.But the specific regula...The main defense response to Soybean mosaic virus(SMV)infection in soybean[Glycine max(L.)Merr.]is thought to be blockage of intercellular virus transport by callose deposition on plasmodesmata.But the specific regulatory mechanism remains largely unknown.In this study,we found that hydrogen peroxide(H_(2)O_(2))signal downstream of NO was associated with the regulation of callose accumulation.Abundant H_(2)O_(2)was produced on the cell membrane and cell wall in the incompatible combination of soybean cultivar Jidou 7 and SMV strain N3,whereas no obvious H_(2)O_(2)was observed in the compatible combination of Jidou 7 and strain SC-8.When H_(2)O_(2)production was inhibited,callose accumulation induced by SMV infection decreased to a level insufficient to restrict virus transport in the incompatible combination.The H_(2)O_(2)-associated transcriptome dynamics of soybean during SMV infection was investigated.Transcriptome and functional analysis using virus-induced gene silencing showed that Gm SEOB and Gm PAP27,two genes regulated by H_(2)O_(2),functioned in resistance by positively regulating the accumulation of callose in response to SMV infection.These results lay a foundation for further research on the signal transduction and molecular regulation of callose deposition during soybean resistance to SMV infection.展开更多
Soybean mosaic virus(SMV)is a member of the genus Potyvirus that extensively impairs global soybean production.The full-length coding sequence of the MADS-box transcription factor Gm CAL was cloned from the SMV-resist...Soybean mosaic virus(SMV)is a member of the genus Potyvirus that extensively impairs global soybean production.The full-length coding sequence of the MADS-box transcription factor Gm CAL was cloned from the SMV-resistant soybean cultivar Kefeng 1.SMV-induced expression analysis indicated that Gm CAL responded quickly to SMV-SC8 infection in Kefeng 1 but not in NN1138-2.Gm CAL was expressed at high levels in flowers and pods but at lower levels in leaves.The gene was localized to the nucleus by subcellular localization assay.Virus-induced gene silencing did not increase the accumulation of SMV in Gm CAL-silenced Kefeng 1 plants(with silencing efficiency~80%)after SC8 inoculation.Gm CAL-silencing plants still conferred resistance to SC8 that might be owing to incomplete silencing of genes with lower expression.SMV content decreased significantly in Gm CAL-overexpressing NN1138-2 plants after SMVSC3,SMV-SC7,and SMV-SC8 inoculation in comparison with a vector control,showing that overexpression of Gm CAL conferred broad-spectrum resistance to multiple SMV strains.These results confirm that Gm CAL,a key regulator but not a specific SC8 resistance gene(Rsc8),is a positive regulatory transcription factor involved in soybean resistance to SMV.展开更多
Soybean mosaic virus(SMV) affects seed quality and production of soybean(Glycine max(L.) Merr.) worldwide.SC18 is one of the dominant SMV strains in South China,and accession Zhonghuang 24 displayed resistance to SC18...Soybean mosaic virus(SMV) affects seed quality and production of soybean(Glycine max(L.) Merr.) worldwide.SC18 is one of the dominant SMV strains in South China,and accession Zhonghuang 24 displayed resistance to SC18.The F_(1),F_(2) and 168 F_(11) recombinant inbred lines(RILs) population derived from a hybridization between Zhonghuang 24(resistant,R) and Huaxia 3(susceptible,S) were used in this study.According to the segregation ratios of the F_(2) generation(3 R:1 S) and the recombinant inbred lines(RILs) population(1 R:1 S),one dominant locus may regulate the resistance to SC18 in Zhonghuang 24.By using composite interval mapping(CIM),Rsc18 was mapped to a 415.357-kb region on chromosome 13.Three candidate genes,including one NBS-LRR type gene and two serine/threonine protein type genes,were identified according to the genetic annotations,which may be related to the resistance to SC18.The q RT-PCR demonstrated that these genes were up-regulated in the R genotype compared to the control.In conclusion,the findings of this research enhanced the understanding about the R genes at the Rsc18 locus.Moreover,our results will provide insights for designing molecular markers to improve marker-assisted selection and developing new varieties with resistance to SC18.展开更多
Soybean mosaic virus (SMV), a member of the genus Potyvirus, is a major pathogen of soybean plants in China, and 16 SMV strains have been identified nationwide based on a former detailed SMV classification system. A...Soybean mosaic virus (SMV), a member of the genus Potyvirus, is a major pathogen of soybean plants in China, and 16 SMV strains have been identified nationwide based on a former detailed SMV classification system. As the P3 gene is thought to be involved in viral replication, systemic infection, pathogenicity, and overcoming resistance, knowledge of the P3 gene sequences of SMV and other potyviruses would be useful in efforts to know the genetic relationships among them and control the disease. P3 gene sequences were obtained from representative isolates of the above-mentioned 16 SMV strains and were compared with other SMV strains and 16 Potyvirus species from the National Center for Biotechnology GenBank database. The P3 genes from the 16 SMV isolates are composed of 1041 nucleotides, encoding 347 amino acids, and share 90.7-100% nucleotide (NT) sequence identities and 95.1-100% amino acid (AA) sequence identities. The P3 coding regions of the 16 SMV isolates share high identities (92.4-98.9% NT and 96.0-100% AA) with the reported Korean isolates, followed by the USA isolates (88.5-97.9% NT and 91.4-98.6% AA), and share low identities (80.5-85.2% NT and 82.1-84.7% AA) with the reported HZ 1 and P isolates from Pinellia ternata. The sequence identities of the P3 genes between SMV and the 16 potyviruses varied from 44.4 to 81.9% in the NT sequences and from 21.4 to 85.3% in the AA sequences, respectively. Among them, SMV was closely related to Watermelon mosaic virus (WMV), with 76.0-81.9% NT and 77.5-85.3% AA identities. In addition, the SMV isolates and potyvirus species were clustered into six distinct groups. All the SMV strains isolated from soybean were clustered in Group I, and the remaining species were clustered in other groups. A multiple sequence alignment analysis of the C-terminal regions indicated that the P3 genes within a species were highly conserved, whereas those among species were relatively variable.展开更多
Soybean mosaic virus(SMV) is one of the most devastating viral pathogens of soybean(Glycine max(L.) Merr). In total, 22 Chinese SMV strains(SC1–SC22) have been classified based on the responses of 10 soybean cultivar...Soybean mosaic virus(SMV) is one of the most devastating viral pathogens of soybean(Glycine max(L.) Merr). In total, 22 Chinese SMV strains(SC1–SC22) have been classified based on the responses of 10 soybean cultivars to these pathogens. However, although several SMVresistance loci in soybean have been identified, no gene conferring SMV resistance in the resistant soybean cultivar(cv.) Kefeng No.1 has been cloned and verified. Here, using F_(2)-derived F_(3)(F_(2:3)) and recombinant inbred line(RIL) populations from a cross between Kefeng No.1 and susceptible soybean cv. Nannong 1138-2, we localized the gene in Kefeng No.1 that mediated resistance to SMV-SC3 strain to a 90-kb interval on chromosome 2. To study the functions of candidate genes in this interval, we performed Bean pod mottle virus(BPMV)-induced gene silencing(VIGS). We identified a recombinant gene(which we named R_(SC3)K) harboring an internal deletion of a genomic DNA fragment partially flanking the LOC100526921 and LOC100812666 reference genes as the SMV-SC3 resistance gene.By shuffling genes between infectious SMV DNA clones based on the avirulent isolate SC3 and virulent isolate 1129, we determined that the viral protein P3 is the avirulence determinant mediating SMV-SC3 resistance on Kefeng No.1. P3 interacts with RNase proteins encoded by R_(SC3)K, LOC100526921, and LOC100812666. The recombinant R_(SC3)K conveys much higher anti-SMV activity than LOC100526921 and LOC100812666, although those two genes also encode proteins that inhibit SMV accumulation, as revealed by gene silencing in a susceptible cultivar and by overexpression in Nicotiana benthamiana. These findings demonstrate that R_(SC3)K mediates the resistance of Kefeng No.1 to SMV-SC3 and that SMV resistance of soybean is determined by the antiviral activity of RNase proteins.展开更多
Soybean mosaic virus (SMV) causes severe yield losses and seed quality reduction in soybean (Glycine max) production worldwide. Rsc4 from cultivar Dabaima is a dominant genetic locus for SMV resistance, and its mappin...Soybean mosaic virus (SMV) causes severe yield losses and seed quality reduction in soybean (Glycine max) production worldwide. Rsc4 from cultivar Dabaima is a dominant genetic locus for SMV resistance, and its mapping interval contains three Nucleotide-binding domain Leucine-rich Repeat containing (NLR) candidates (Rsc4-1, Rsc4-2, and Rsc4-3). The NLR-type resistant proteins were considered as important intracellular pathogen sensors in the previous studies. In this research, based on transient expression assay in Nicotiana benthamiana leaves, we found that the longest transcript of Rsc4-3 is sufficient to induce resistance response to SMV;and CRISPR/Cas9-mediated Rsc4-3 knockout in resistant cultivar Dabaima compromised the resistance. These indicate that Rsc4-3 confers resistance to SMV. Interestingly, Rsc4-3 encodes a cell wall localized NLR-type resistant protein (Rsc4-3). The internal polypeptide region responsible for apoplastic targeting of Rsc4-3 and the putative palmitoylation sites on the N-terminus are essential for the resistance response. Furthermore, we showed that viral-encoded cylindrical inclusion (CI) protein partially localizes to the cell wall and can interact with Rsc4-3. Virus-driven or transient expression of CI protein of avirulent SMV strains is enough to induce resistance response in the presence of Rsc4-3, suggesting that CI is the avirulent gene for Rsc4-3 mediated resistance. Our work exhibited a case of NLR recognizing virus in the apoplast and provided a simple and effective method for identifying resistant genes against SMV infection.展开更多
Soybean mosaic virus (SMV) is one of the most serious diseases affecting soy-bean yield. Recombination inbred lines (RILs) are common materials for resistance genetic research. However, the population constructi...Soybean mosaic virus (SMV) is one of the most serious diseases affecting soy-bean yield. Recombination inbred lines (RILs) are common materials for resistance genetic research. However, the population construction always takes quite a long time which pro-long the breading process. Shoot-cutting is a well-established technique for plant multipli-cation. It has high successful ratio in soybean. In this study, we use shoot-cutting to multiply two F2 populations from the crosses of susceptible and resistant varieties. Soybean plants can be multiplied from 1 into 3 homogenous ones within 30 days, bringing on well-grown plants with normal seeds. The SMV resistance from cutting-shoot plants was consistent with that from original plants. When shoot-cutting is applied in a F2 population, the pheno-typic and genotypic data can be simultaneously collected and corresponding saved during population development. The genetic research and resistant breeding can be effectively promoted by this technology.展开更多
Soybean mosaic virus (SMV) is one of the most broadly distributed diseases worldwide. It causes severe yield loss and seed quality deficiency in soybean (Glycine max (L.) Merr.). SMV Strain SC14 isolated from Sh...Soybean mosaic virus (SMV) is one of the most broadly distributed diseases worldwide. It causes severe yield loss and seed quality deficiency in soybean (Glycine max (L.) Merr.). SMV Strain SC14 isolated from Shanxi Province, China, was a newly identified virulent strain and can infect Kefeng No. 1, a source with wide spectrum resistance. In the present study, soybean accessions, PI96983, Qihuang No. 1 and Qihuang No. 22 were identified to be resistant (R) and Nannong 1138-2, Pixianchadou susceptible (S) to SC14. Segregation analysis of PI96983 x Nannong 1138-2 indicated that a single dominant gene (designated as Rsc14) controlled the resistance to SC14 at both V2 and R1 developmental stages. The same results were obtained for the crosses of Qihuang No. 1 × Nannong 1138-2 and Qihuang No. 22 x Nannong 1138-2 as in PI96983 x×Nannong 1138-2 at V2 stage, but at R1 stage, the F1 performed as necrosis (a susceptible symptom other than mosaic), F2 segregated in a ratio of 1R:2N:IS, and the progenies of necrotic (N) F2 individuals segregated also in R, N and S. It indicated that a single gene (designated as Rsc140, to be different from that of PI96983) controlled the resistance to SC14, its dominance was the same as in PI96983 × Nannong 1138-2 (without symptoms) at V2 stage and not the same at R1 stage. The tightly linked co-dominant simple sequence repeat (SSR) marker Satt334 indicated that all the heterozygous bands were completely corresponding to the necrotic F2 individuals, or all the necrotic F2 individuals were heterozygotes. It was inferred that necrosis might be due to the interaction among SMV strains, resistance genes, genetic background of the resistance genes, and plant development stage. Furthermore, the bulked segregant analysis (BSA) of SSR markers was conducted to map the resistance genes. In F2 of PI96983 × Nannong 1138-2, five SSR markers, Sat_297, Sat_234, Sat_154, Sct_033 and Sat_120, were found closely linked to Rsc14, with genetic distances of 14.5 cM, 11.3 cM, 4.3 cM, 3.2 cM and 6 cM, respectively. In F2 of Qihuang No. 1 × Nannong 1138-2,three SSR markers, Sat_234, Satt334 and Sct_033, tightly linked to Rsc140 with genetic distances of 7.2 cM, 1.4 cM and 2.8 cM, respectively. Based on the integrated joint map by Cregan et al. (1999), both Rsc14 and Rsc140 were located between Sat_234 and Sct_033 on linkage with group F of soybean, with their distances from Sct_033 at the same side being 3.2 cM and 2.8 cM, respectively. Therefore, Rsc14 and Rsc140 might be on a same locus. The obtained information provides a basic knowledge for marker-assisted selection of the resistance gene in soybean breeding programs and fine mapping and map-based cloning of the resistance gene.展开更多
Soybean is a crop with a long cultivation history that occupies an important position in agricultural production.Soybean mosaic virus disease(SMV)has caused a rapid decline in soybean yields,causing huge losses to the...Soybean is a crop with a long cultivation history that occupies an important position in agricultural production.Soybean mosaic virus disease(SMV)has caused a rapid decline in soybean yields,causing huge losses to the soybean industry,wherefrom its early detec-tion is particularly important.This study proposes a new classification method for the early SMV,dividing its severity into grades 0,1 and 2.In the case of a small number of experi-mental samples of soybeans,this study proposes a combined convolutional neural network and support vector machine(CNN-SVM)method for the early detection of SMV.Experimen-tal results showed that the accuracy of the training set of the CNN-SVM model reached 96.67%,and the accuracy rate of the test set reached 94.17%.The experiment proved the feasibility of using the proposed CNN-SVM model to classify early SMV under the new clas-sification method,and provided a new direction for early SMV detection based on hyper-spectral images.展开更多
Soybean mosaic virus(SMV) disease is one of the most serious and broadly distributed soybean(Glycine max(L.) Merr.) diseases. Here, we combine the advantages of association and linkage analysis to identify and f...Soybean mosaic virus(SMV) disease is one of the most serious and broadly distributed soybean(Glycine max(L.) Merr.) diseases. Here, we combine the advantages of association and linkage analysis to identify and fine-map the soybean genes associated with resistance to SMV strain SC7.A set of 191 soybean accessions from different geographic origins and 184 recombinant inbred lines(RILs) derived from Kefeng No.1(resistant) Nannong 1138-2(susceptible) were used in this study. The SC7 resistance genes were previously mapped to a 2.65 Mb region on chromosome 2 and a 380 kb region on chromosome 13. Among 19 single nucleotide polymorphisms(SNPs) detected via association analysis in the study, the SNP BARC-021625-04157 was located in the2.65 Mb region, and the SNP BARC-041671-08065 was located near the 380 kb region; three genes harboring the SNPs were probably related to SC7 resistance. The resistance gene associated with BARC-021625-04157 was then finemapped to a region of approximately 158 kb on chromosome2 using 184 RILs. Among the 15 genes within this region, one NBS-LRR type gene, one HSP40 gene and one serine carboxypeptidase-type gene might be candidate SC7 resistance genes. These results will be useful for map-based cloning and marker-assisted selection in soybean breeding programs.展开更多
基金supported by grants from National Natural Science Foundation of China(32001571)R&D Program of Beijing Municipal Education Commission(KM202212448003,KM202312448004)+4 种基金Science and Technology Innovation Project of Beijing Vocational College of Agriculture(XY-YF-22-02)Zhongshan Biological Breeding Laboratory(ZSBBL-KY2023-03)China Agriculture Research System of MOF and MARA(CARS-04)Jiangsu Collaborative Innovation Center for Modern Crop Production(JCICMCP)Collaborative Innovation Center for Modern Crop Production co-sponsored by Province and Ministry(CIC-MCP).
文摘Soybean mosaic virus(SMV),an RNA virus,is the most common and destructive pathogenic virus in soybean fields.The newly developed CRISPR/Cas immune system has provided a novel strategy for improving plant resistance to viruses;hence,this study aimed to engineer SMV resistance in soybean using this system.Specifically,multiple sgRNAs were designed to target positive-and/or negative-sense strands of the SMV HC-Pro gene.Subsequently,the corresponding CRISPR/CasRx vectors were constructed and transformed into soybeans.After inoculation with SMV,39.02%,35.77%,and 18.70%of T_(1)plants were confirmed to be highly resistant(HR),resistant(R),and mildly resistant(MR)to SMV,respectively,whereas only 6.50%were identified as susceptible(S).Additionally,qRT-PCR and DAS-ELISA showed that,both at 15 and 30 d post-inoculation(dpi),SMV accumulation significantly decreased or was even undetectable in HR and R plants,followed by MR and S plants.Additionally,the expression level of the CasRx gene varied in almost all T_(1)plants with different resistance level,both at 15 and 30 dpi.Furthermore,when SMV resistance was evaluated in the T_(2)generation,the results were similar to those recorded for the T_(1)generation.These findings provide new insights into the application of the CRISPR/CasRx system for soybean improvement and offer a promising alternative strategy for breeding for resistance to biotic stress that will contribute to the development of SMV-immune soybean germplasm to accelerate progress towards greater soybean crop productivity.
基金the National Natural Science Foundation of China(32001502,32001507)the China Postdoctoral Science Foundation(2020M682655)+3 种基金the top ten critical priorities of Agricultural Science and Technology Innovations for the 14th Five-Year Plan of Guangdong Province(2022SDZG05)Science and Technology Innovation Team of Soybean Modern Seed Industry In Hebei Province(21326313D-4)Innovation Research Project of Coarse Cereals Specialty in Guizhou Province[2019[4012]]the Regional First-class Discipline of Ecology in Guizhou Province(XKTJ[2020]22).
文摘Soybean(Glycine max)is a major oil and feed crop worldwide.Soybean mosaic virus(SMV)is a globally occurring disease that severely reduces the yield and quality of soybean.Here,we characterized the role of the clock gene TIMING OF CAB EXPRESSION 1b(GmTOC1b)in the resistance of soybean to SMV.Homozygous Gmtoc1b mutants exhibited increased tolerance to SMV strain SC3 due to the activation of programmed cell death triggered by a hypersensitive response.Transcriptome deep sequencing and RT-qPCR analysis suggested that GmTOC1b likely regulates the expression of target genes involved in the salicylic acid(SA)signaling pathway.GmTOC1b binds to the promoter of GmWRKY40,which encodes a protein that activates the expression of SA-mediated defense-related genes.Moreover,we revealed that the GmTOC1bH1 haplotype,which confers increased tolerance to SMV,was artificially selected in improved cultivars from the Northern and Huang-Huai regions of China.Our results therefore identify a previously unknown SMV resistance component that could be deployed in the molecular breeding of soybean to enhance SMV resistance.
文摘Soybean mosaic virus (SMV) causes one of the most severe viral diseases in soybean ( Glycine max L.) and is known to contain many pathogenically and serologically related isolates. In the present study, the authors have obtained cDNAs to all cistrons of a Chinese SMV isolate, SMV_ZK, by RT_PCR. By analysing the nucleotide and amino acid sequence of the HC_PRO, NIb and CP cistrons, it was found that SMV_ZK was highly homologous to the G2 strain of SMV, thus confirming the existence of G2_like isolates in soybean crop in China. The amplified cDNAs were directly cloned into a bacterial expression vector. With the exception of the P3 cistron, expression of the cDNAs of all other cistrons in bacteria gave rise to polypeptides of expected molecular weight. The expressed viral proteins were subsequently purified by gel elution. The preparation of viral_specific cDNAs and gene products will be useful in future functional study of the SMV genome.
基金supported by the National Natural Science Foundation of China (31171574, 31371646)the National Soybean Industrial Technology System of China (CARS-004)the Fund for Transgenic Breeding of Soybean Resistant to Soybean Mosaic Virus, China (2008ZX08004-004)
文摘Soybean mosaic virus (SMV) disease is one of the most destructive viral diseases in soybean (Glycine max (L.) Merr.). SMV strain SC3 is the major prevalent strain in huang-huai and Yangtze valleys, China. The soybean cultivar Qihuang 1 is of a rich resistance spectrum and has a wide range of application in breeding programs in China. In this study, F1, F2 and F2:3 from Qihuang 1×nannong 1138-2 were used to study inheritance and linkage mapping of the SC3 resistance gene in Qihuang 1. The secondary F2 population and near isogenic lines (nILs) derived from residual heterozygous lines (RhLs) of Qihuang 1×nannong 1138-2 were separatively used in the ifne mapping and candidate gene analysis of the resistance gene. Results indicated that a single dominant gene (designated RSC3Q) controls resistance, which was located on chromosome 13. Two genomic-simple sequence repeat (SSR) markers BARCSOYSSR_13_1114 and BARCSOYSSR_13_1136 were found lfanking the two sides of the RSC3Q. The interval between the two markers was 651 kb. Quantitative real-time PCR analysis of the candidate genes showed that ifve genes (Glyma13g25730, 25750, 25950, 25970 and 26000) were likely involved in soybean SMV resistance. These results would have utility in cloning of RSC3Q resistance candidate gene and marker-assisted selection (MaS) in resistance breeding to SMV.
基金supported by the National Natura1 Science Foundation of China(30170607).
文摘A sample composed of 96 soybean accessions was evaluated for their diseased rate (I),diseased rank (S), latent period (LP) and rate of disease development (R) in order tostudy the quantitative resistance to soybean mosaic virus (SMV) in soybeans. The resultsshowed that the performances of the above four resistance components were significantlydifferent among accessions and that some of the accessions, such as Zhongzihuangdou,Peixian Tianedan, Youbian30 could be infected by four SMV strains, Sa, SC8, N1 and N3,but their I, S, and R were lower and LP longer than most other accessions. These resultsdemonstrated the existence of quantitative resistance to SMV in soybeans. It was foundthat some soybean accessions, such as AGS19 and Lishui Zhongzihuangdou, previouslyidentified as resistant to SMV infection, performed some infection but resistant toexpansion in the present study. In addition, the resistance in Pixian Chadou and HuaiyinQiuheidou might be either qualitative or quantitative. Furthermore, the present studyalso indicated that the resistance spectrum and durability of accessions with quantitativeresistance might be wider and longer than those with qualitative resistance.
基金supported by the National Natural Science Foundation of China(31571687,31571690,and 31371646)the Natural Science Foundation of Anhui Province,China(1708085MC69)+1 种基金the Jiangsu Collaborative Innovation Center for Modern Crop Production,China(JCIC-MCP)the Fund of Transgenic Breeding for Soybean Resistance to Soybean Mosaic Virus,China(2016ZX08004-004)
文摘Soybean mosaic virus (SMV) is one of the major viral pathogens affecting soybean crops worldwide. Three SMV resistance genes, Rsc4, Rsc8, and Rsc14Q, have been identified and mapped on soybean chromosomes 14, 2, and 13 from Dabaima, Kefeng 1, and Qihuang 1 cultivars, respectively. Soybean cultivar Nannong 1138-2 is widely grown in the Yangtze River Valley of China. In this study, crosses were made between Qihuang l^Kefeng 1 and DabaimaxNannong 1138-2. Ten simple sequence repeat (SSR) markers linked to three resistance loci (Rsc4, Rsc8, and Rsc^4Q) were used to assist pyramided breeding. Pyramided families containing three resistance loci (Rsc4, Rsc8, and Rsc14Q) were evaluated by inoculating them with 21 SMV strains from China. Results indicated that the 10 markers can be used effectively to assist the selection of resistant individuals containing Rsc4, Rsc8, and Rsc14Q. A total of 53 F6 plants were confirmed to contain three homozygous alleles conferring resistance to SMV. Five F7 homozygous pyramided families exhibited resistance to 21 strains of SMV and showed desirable agronomic traits using dual selection. The strategy of pyramiding resistance gene derived from different varieties has practical breeding value in providing broad-spectrum resistance against the existing strains of SMV in China.
基金supported by the National Natural Science Foundation of China(30971706 and31471421)"973"Preliminary Program(2014CB160318)Hebei Natural Science Foundation(C2020204132)。
文摘The main defense response to Soybean mosaic virus(SMV)infection in soybean[Glycine max(L.)Merr.]is thought to be blockage of intercellular virus transport by callose deposition on plasmodesmata.But the specific regulatory mechanism remains largely unknown.In this study,we found that hydrogen peroxide(H_(2)O_(2))signal downstream of NO was associated with the regulation of callose accumulation.Abundant H_(2)O_(2)was produced on the cell membrane and cell wall in the incompatible combination of soybean cultivar Jidou 7 and SMV strain N3,whereas no obvious H_(2)O_(2)was observed in the compatible combination of Jidou 7 and strain SC-8.When H_(2)O_(2)production was inhibited,callose accumulation induced by SMV infection decreased to a level insufficient to restrict virus transport in the incompatible combination.The H_(2)O_(2)-associated transcriptome dynamics of soybean during SMV infection was investigated.Transcriptome and functional analysis using virus-induced gene silencing showed that Gm SEOB and Gm PAP27,two genes regulated by H_(2)O_(2),functioned in resistance by positively regulating the accumulation of callose in response to SMV infection.These results lay a foundation for further research on the signal transduction and molecular regulation of callose deposition during soybean resistance to SMV infection.
基金the National Key Research and Development Program of China(2017YFD0101500)the National Natural Science Foundation of China(31671718)+3 种基金and China Agriculture Research System of MOF and MARA(CARS-04)the Jiangsu Collaborative Innovation Center for Modern Crop Production(JCICMCP)Collaborative Innovation Center for Modern Crop Production co-sponsored by Province and Ministry(CIC-MCP)the Program for Changjiang Scholars and Innovative Research Team in University(PCSIRT_17R55)。
文摘Soybean mosaic virus(SMV)is a member of the genus Potyvirus that extensively impairs global soybean production.The full-length coding sequence of the MADS-box transcription factor Gm CAL was cloned from the SMV-resistant soybean cultivar Kefeng 1.SMV-induced expression analysis indicated that Gm CAL responded quickly to SMV-SC8 infection in Kefeng 1 but not in NN1138-2.Gm CAL was expressed at high levels in flowers and pods but at lower levels in leaves.The gene was localized to the nucleus by subcellular localization assay.Virus-induced gene silencing did not increase the accumulation of SMV in Gm CAL-silenced Kefeng 1 plants(with silencing efficiency~80%)after SC8 inoculation.Gm CAL-silencing plants still conferred resistance to SC8 that might be owing to incomplete silencing of genes with lower expression.SMV content decreased significantly in Gm CAL-overexpressing NN1138-2 plants after SMVSC3,SMV-SC7,and SMV-SC8 inoculation in comparison with a vector control,showing that overexpression of Gm CAL conferred broad-spectrum resistance to multiple SMV strains.These results confirm that Gm CAL,a key regulator but not a specific SC8 resistance gene(Rsc8),is a positive regulatory transcription factor involved in soybean resistance to SMV.
基金supported by the projects of the Key-Areas Research and Development Program of Guangdong Province, China (2020B020220008)the China Agriculture Research System of MOF and MARA (CARS-04-PSO9)+2 种基金the Major Project of New Varieties Cultivation of Genetically Modified Varieties, China (2016ZX08004002-007)the National Key R&D Program of China (2017FYD0101500)the National Natural Science Foundation of China (31971966)。
文摘Soybean mosaic virus(SMV) affects seed quality and production of soybean(Glycine max(L.) Merr.) worldwide.SC18 is one of the dominant SMV strains in South China,and accession Zhonghuang 24 displayed resistance to SC18.The F_(1),F_(2) and 168 F_(11) recombinant inbred lines(RILs) population derived from a hybridization between Zhonghuang 24(resistant,R) and Huaxia 3(susceptible,S) were used in this study.According to the segregation ratios of the F_(2) generation(3 R:1 S) and the recombinant inbred lines(RILs) population(1 R:1 S),one dominant locus may regulate the resistance to SC18 in Zhonghuang 24.By using composite interval mapping(CIM),Rsc18 was mapped to a 415.357-kb region on chromosome 13.Three candidate genes,including one NBS-LRR type gene and two serine/threonine protein type genes,were identified according to the genetic annotations,which may be related to the resistance to SC18.The q RT-PCR demonstrated that these genes were up-regulated in the R genotype compared to the control.In conclusion,the findings of this research enhanced the understanding about the R genes at the Rsc18 locus.Moreover,our results will provide insights for designing molecular markers to improve marker-assisted selection and developing new varieties with resistance to SC18.
基金supported by the National Natural Science Foundation of China(30671266,31101164)the National Basic Research Program of China(2006CB101708,2009CB118404)+2 种基金the National 863 Program of China(2006AA100104)the 111 Project from Ministry of Education of China(B08025)the Youth Science and Technology Innovation Foundation of Nanjing Agriculture University,China(KJ2010002)
文摘Soybean mosaic virus (SMV), a member of the genus Potyvirus, is a major pathogen of soybean plants in China, and 16 SMV strains have been identified nationwide based on a former detailed SMV classification system. As the P3 gene is thought to be involved in viral replication, systemic infection, pathogenicity, and overcoming resistance, knowledge of the P3 gene sequences of SMV and other potyviruses would be useful in efforts to know the genetic relationships among them and control the disease. P3 gene sequences were obtained from representative isolates of the above-mentioned 16 SMV strains and were compared with other SMV strains and 16 Potyvirus species from the National Center for Biotechnology GenBank database. The P3 genes from the 16 SMV isolates are composed of 1041 nucleotides, encoding 347 amino acids, and share 90.7-100% nucleotide (NT) sequence identities and 95.1-100% amino acid (AA) sequence identities. The P3 coding regions of the 16 SMV isolates share high identities (92.4-98.9% NT and 96.0-100% AA) with the reported Korean isolates, followed by the USA isolates (88.5-97.9% NT and 91.4-98.6% AA), and share low identities (80.5-85.2% NT and 82.1-84.7% AA) with the reported HZ 1 and P isolates from Pinellia ternata. The sequence identities of the P3 genes between SMV and the 16 potyviruses varied from 44.4 to 81.9% in the NT sequences and from 21.4 to 85.3% in the AA sequences, respectively. Among them, SMV was closely related to Watermelon mosaic virus (WMV), with 76.0-81.9% NT and 77.5-85.3% AA identities. In addition, the SMV isolates and potyvirus species were clustered into six distinct groups. All the SMV strains isolated from soybean were clustered in Group I, and the remaining species were clustered in other groups. A multiple sequence alignment analysis of the C-terminal regions indicated that the P3 genes within a species were highly conserved, whereas those among species were relatively variable.
基金supported by the National Key R&D Program of China (2021YFD1201604)Jiangsu Collaborative Innovation Center for Modern Crop Production (JCIC-MCP)+1 种基金the Core Technology Development for Breeding Program of Jiangsu Province (JBGS-2021-014)China Agriculture Research System of MOF and MARA (No. CARS-04)。
文摘Soybean mosaic virus(SMV) is one of the most devastating viral pathogens of soybean(Glycine max(L.) Merr). In total, 22 Chinese SMV strains(SC1–SC22) have been classified based on the responses of 10 soybean cultivars to these pathogens. However, although several SMVresistance loci in soybean have been identified, no gene conferring SMV resistance in the resistant soybean cultivar(cv.) Kefeng No.1 has been cloned and verified. Here, using F_(2)-derived F_(3)(F_(2:3)) and recombinant inbred line(RIL) populations from a cross between Kefeng No.1 and susceptible soybean cv. Nannong 1138-2, we localized the gene in Kefeng No.1 that mediated resistance to SMV-SC3 strain to a 90-kb interval on chromosome 2. To study the functions of candidate genes in this interval, we performed Bean pod mottle virus(BPMV)-induced gene silencing(VIGS). We identified a recombinant gene(which we named R_(SC3)K) harboring an internal deletion of a genomic DNA fragment partially flanking the LOC100526921 and LOC100812666 reference genes as the SMV-SC3 resistance gene.By shuffling genes between infectious SMV DNA clones based on the avirulent isolate SC3 and virulent isolate 1129, we determined that the viral protein P3 is the avirulence determinant mediating SMV-SC3 resistance on Kefeng No.1. P3 interacts with RNase proteins encoded by R_(SC3)K, LOC100526921, and LOC100812666. The recombinant R_(SC3)K conveys much higher anti-SMV activity than LOC100526921 and LOC100812666, although those two genes also encode proteins that inhibit SMV accumulation, as revealed by gene silencing in a susceptible cultivar and by overexpression in Nicotiana benthamiana. These findings demonstrate that R_(SC3)K mediates the resistance of Kefeng No.1 to SMV-SC3 and that SMV resistance of soybean is determined by the antiviral activity of RNase proteins.
基金This work was supported by the National Natural Science Foundation of China(31571690,31770164)the Fundamental Research Funds for the Central Universities(KYT201801)+3 种基金Program for Changjiang Scholars and Innovative Research Team in University(PCSIRT_17R55)the National Soybean Industrial Technology System of China(CARS-004)Jiangsu Collaborative Innovation Center for Modern Crop Production(JCIC-MCP),the National Key R&D Program of China(2017YFD0101501)the Natural Science Foundation of Jiangsu Province(BK20180039).
文摘Soybean mosaic virus (SMV) causes severe yield losses and seed quality reduction in soybean (Glycine max) production worldwide. Rsc4 from cultivar Dabaima is a dominant genetic locus for SMV resistance, and its mapping interval contains three Nucleotide-binding domain Leucine-rich Repeat containing (NLR) candidates (Rsc4-1, Rsc4-2, and Rsc4-3). The NLR-type resistant proteins were considered as important intracellular pathogen sensors in the previous studies. In this research, based on transient expression assay in Nicotiana benthamiana leaves, we found that the longest transcript of Rsc4-3 is sufficient to induce resistance response to SMV;and CRISPR/Cas9-mediated Rsc4-3 knockout in resistant cultivar Dabaima compromised the resistance. These indicate that Rsc4-3 confers resistance to SMV. Interestingly, Rsc4-3 encodes a cell wall localized NLR-type resistant protein (Rsc4-3). The internal polypeptide region responsible for apoplastic targeting of Rsc4-3 and the putative palmitoylation sites on the N-terminus are essential for the resistance response. Furthermore, we showed that viral-encoded cylindrical inclusion (CI) protein partially localizes to the cell wall and can interact with Rsc4-3. Virus-driven or transient expression of CI protein of avirulent SMV strains is enough to induce resistance response in the presence of Rsc4-3, suggesting that CI is the avirulent gene for Rsc4-3 mediated resistance. Our work exhibited a case of NLR recognizing virus in the apoplast and provided a simple and effective method for identifying resistant genes against SMV infection.
文摘Soybean mosaic virus (SMV) is one of the most serious diseases affecting soy-bean yield. Recombination inbred lines (RILs) are common materials for resistance genetic research. However, the population construction always takes quite a long time which pro-long the breading process. Shoot-cutting is a well-established technique for plant multipli-cation. It has high successful ratio in soybean. In this study, we use shoot-cutting to multiply two F2 populations from the crosses of susceptible and resistant varieties. Soybean plants can be multiplied from 1 into 3 homogenous ones within 30 days, bringing on well-grown plants with normal seeds. The SMV resistance from cutting-shoot plants was consistent with that from original plants. When shoot-cutting is applied in a F2 population, the pheno-typic and genotypic data can be simultaneously collected and corresponding saved during population development. The genetic research and resistant breeding can be effectively promoted by this technology.
基金Supported by the State Key Basic Research and Development Plan of China (2004CB117203-2 and 2002CB111304), the National Natural Science Foundation of China (30571176 and 30490250), the Natural Science Foundation of Jiangsu Province (BK2004100) and the Program for Changjiang Scholars and Innovative Research Team in University (PCSIRT).
文摘Soybean mosaic virus (SMV) is one of the most broadly distributed diseases worldwide. It causes severe yield loss and seed quality deficiency in soybean (Glycine max (L.) Merr.). SMV Strain SC14 isolated from Shanxi Province, China, was a newly identified virulent strain and can infect Kefeng No. 1, a source with wide spectrum resistance. In the present study, soybean accessions, PI96983, Qihuang No. 1 and Qihuang No. 22 were identified to be resistant (R) and Nannong 1138-2, Pixianchadou susceptible (S) to SC14. Segregation analysis of PI96983 x Nannong 1138-2 indicated that a single dominant gene (designated as Rsc14) controlled the resistance to SC14 at both V2 and R1 developmental stages. The same results were obtained for the crosses of Qihuang No. 1 × Nannong 1138-2 and Qihuang No. 22 x Nannong 1138-2 as in PI96983 x×Nannong 1138-2 at V2 stage, but at R1 stage, the F1 performed as necrosis (a susceptible symptom other than mosaic), F2 segregated in a ratio of 1R:2N:IS, and the progenies of necrotic (N) F2 individuals segregated also in R, N and S. It indicated that a single gene (designated as Rsc140, to be different from that of PI96983) controlled the resistance to SC14, its dominance was the same as in PI96983 × Nannong 1138-2 (without symptoms) at V2 stage and not the same at R1 stage. The tightly linked co-dominant simple sequence repeat (SSR) marker Satt334 indicated that all the heterozygous bands were completely corresponding to the necrotic F2 individuals, or all the necrotic F2 individuals were heterozygotes. It was inferred that necrosis might be due to the interaction among SMV strains, resistance genes, genetic background of the resistance genes, and plant development stage. Furthermore, the bulked segregant analysis (BSA) of SSR markers was conducted to map the resistance genes. In F2 of PI96983 × Nannong 1138-2, five SSR markers, Sat_297, Sat_234, Sat_154, Sct_033 and Sat_120, were found closely linked to Rsc14, with genetic distances of 14.5 cM, 11.3 cM, 4.3 cM, 3.2 cM and 6 cM, respectively. In F2 of Qihuang No. 1 × Nannong 1138-2,three SSR markers, Sat_234, Satt334 and Sct_033, tightly linked to Rsc140 with genetic distances of 7.2 cM, 1.4 cM and 2.8 cM, respectively. Based on the integrated joint map by Cregan et al. (1999), both Rsc14 and Rsc140 were located between Sat_234 and Sct_033 on linkage with group F of soybean, with their distances from Sct_033 at the same side being 3.2 cM and 2.8 cM, respectively. Therefore, Rsc14 and Rsc140 might be on a same locus. The obtained information provides a basic knowledge for marker-assisted selection of the resistance gene in soybean breeding programs and fine mapping and map-based cloning of the resistance gene.
基金This work is supported by National Natural Science Founda-tion of China(NSFC)(32071904)。
文摘Soybean is a crop with a long cultivation history that occupies an important position in agricultural production.Soybean mosaic virus disease(SMV)has caused a rapid decline in soybean yields,causing huge losses to the soybean industry,wherefrom its early detec-tion is particularly important.This study proposes a new classification method for the early SMV,dividing its severity into grades 0,1 and 2.In the case of a small number of experi-mental samples of soybeans,this study proposes a combined convolutional neural network and support vector machine(CNN-SVM)method for the early detection of SMV.Experimen-tal results showed that the accuracy of the training set of the CNN-SVM model reached 96.67%,and the accuracy rate of the test set reached 94.17%.The experiment proved the feasibility of using the proposed CNN-SVM model to classify early SMV under the new clas-sification method,and provided a new direction for early SMV detection based on hyper-spectral images.
基金supported in part by the National Basic Research Program of China(973 Program)(2010CB125906)the National Natural Science Foundation of China(31171573,31301342,31370034)+2 种基金the Jiangsu Provincial Support Program(BE2012328)the Program for Changjiang Scholarsthe Innovative Research Team in University(PCSIRT13073)
文摘Soybean mosaic virus(SMV) disease is one of the most serious and broadly distributed soybean(Glycine max(L.) Merr.) diseases. Here, we combine the advantages of association and linkage analysis to identify and fine-map the soybean genes associated with resistance to SMV strain SC7.A set of 191 soybean accessions from different geographic origins and 184 recombinant inbred lines(RILs) derived from Kefeng No.1(resistant) Nannong 1138-2(susceptible) were used in this study. The SC7 resistance genes were previously mapped to a 2.65 Mb region on chromosome 2 and a 380 kb region on chromosome 13. Among 19 single nucleotide polymorphisms(SNPs) detected via association analysis in the study, the SNP BARC-021625-04157 was located in the2.65 Mb region, and the SNP BARC-041671-08065 was located near the 380 kb region; three genes harboring the SNPs were probably related to SC7 resistance. The resistance gene associated with BARC-021625-04157 was then finemapped to a region of approximately 158 kb on chromosome2 using 184 RILs. Among the 15 genes within this region, one NBS-LRR type gene, one HSP40 gene and one serine carboxypeptidase-type gene might be candidate SC7 resistance genes. These results will be useful for map-based cloning and marker-assisted selection in soybean breeding programs.